The present invention relates to cranes and analogous machines in general, and more particularly to improvements in attachments for the booms of cranes or the like. Still more particularly, the invention relates to improvements in an attachment which can be separably or permanently coupled to the preferably extensible (variable-length) boom of a crane or an analogous machine and can carry one or more persons who are to perform work on the facades of tall buildings, at the undersides, along the sides or on other parts of bridges or viaducts, on tall chimneys, poles or masts, along the surfaces of rocks, cliffs or hills, and/or in analogous situations where the work must be performed at the hard-to-reach exposed sides of buildings or the like. A machine which is equipped with the attachment of the present invention can be used with equal advantage by fruit gatherers, firemen, policemen, shipyard workers, aircraft maintenance personnel and others.
It is well known to equip a crane with one or more elongated booms whose length can be increased or reduced (either mechanically or by fluid-operated means), which can be rotated about their respective axes, and/or whose inclination can be changed through an angle of up to or even in excess of 90 degrees (e.g., between a horizontal and a vertical position). Reference may be had to U.S. Pat. Nos. 2,632,530 to Wagner and 2,821,312 to Wiegel which disclose cranes or analogous machines with extensible and adjustable booms. The disclosures of these patents are incorporated herein by reference.
It is further known to attach to the free end portion of the boom of a crane a basket or another type of receptacle (hereinafter called gallery) for one or more persons and/or for cargo. As a rule, the gallery is suspended on a cable, chain, cord or an analogous flexible element which is trained over one or more pulleys at the free end of the boom. In many instances, the gallery comprises a substantially rectangular or square floor and four railings or walls which extend upwardly from and above the floor to enhance the safety of the person or persons occupying the gallery and/or to prevent the cargo from sliding off the floor in response to swaying of the gallery and/or in response to abrupt changes of inclination of the boom.
Many cranes are motorized so that they can be readily transferred between different locales of use and/or to or from the owner's or user's yard. Since the width of the gallery normally greatly exceeds the width of the boom, it is customary to detach the gallery from the end portion of the boom prior to driving the crane to the yard, from the yard, or from one locale of use to the next locale. This is a time-consuming operation, and the transport of the gallery normally involves the use of a discrete vehicle. Alternatively, the crane must be accompanied by a detachment of security personnel to ensure that the road is free and the gallery at the free end of the crane is capable of passing below bridges, overpasses or viaducts as well as that the moving crane, with the boom extended forwardly or folded rearwardly, can take the curves and bypass other types of obstacles. All this is very cumbersome and contributes significantly to the cost of using the crane.